Seperation techniques

Mixtures are easily separated, no chemical bond.

  • Paper chromatography:

    1. Draw a line (pencil) near bottom of a sheet of filter paper

    2. Add spot of ink to the line and place sheet in a beaker of solvent (water)

    3. Make sure the ink spot is above the water

    4. Place a lid on top to stop evaporation

    5. The solvent will seep up the paper and carry the ink with it

    6. Each different dye in the ink will move up at a different rate and will thus separate

    7. When the solvent is almost at the top of the paper remove it from the beaker

  • Filtration

    • Can be used if your product is an insoluble solid that needs to be separated from a liquid

    • Also can be used in purification.

  • Evaporation

    • Used to separate soluble solids from solutions

      1. Pour the solution into an evaporating dish

      2. Slowly heat the solution using a Bunsen burner. The solvent will evaporate and the solution will get more concentrated

      3. Eventually the solution will evaporate and you will be left with dry crystals

  • Crystallisation

    • Separate soluble solids from solution

      1. Pour solution into evaporating dish and gently heat, some solvent will evaporate and solution will be more concentrated.

      2. When you see crystals start to form (point of crystallisation), remove the dish from heat and leave solution to cool.

      3. Should start to form crystals as it becomes insoluble in the cold, highly concentrated solution.

      4. Filter out the crystals and leave them in a warm place to dry.

  • Distillation

    • Simple distillation

      • Used to separate mixtures which contain liquids

        1. Solution is heated using a Bunsen burner, the liquid in the solution with the lowest boiling point will start to evaporate first

        2. As it evaporated it will enter a condenser, the vapour is cooled here and turned back into a liquid

        3. It then exits the condensing tube into a beaker, where the solutions are separate.

    • Fractional Distillation

      • Used to separate mixtures with liquids which have similar boiling points

        1. Put your mixture in a flask and put a fractionating column on top and then begin to heat it up

        2. As it heats the liquid with the lowest boiling point will evaporate first, when the temperature on the thermometer matches its boiling point it will reach the top of the column and then enter a condensing tube and separate into another beaker

        3. Liquids with higher boiling points may also start to evaporate but the column is cooler near the top so they will only get part of the way up before condensing and running back down into the flask.